Two genotypes (I and II) of Bartonella henselae are involved in cat-scratch disease (CSD). Lymph node biopsies were taken from 3 children suffering from CSD, and blood cultures were obtained from their pet cats. Cat-scratch disease was confirmed serologically, histologically and by detection of B. henselae DNA in all 3 lymph nodes by PCR. Bartonella henselae grew in all cats' blood cultures. The first 2 children were siblings. Both children and their pet cats were infected with B. henselae genotype II, and the third patient and her cat were infected with B. henselae genotype I. In all cases, there were no essential differences in the clinical manifestations of the infection caused by these 2 genotypes of B. henselae.